Top hat bearing retainer for variable vane actuator

ABSTRACT

A variable vane actuation system with a plurality of vanes which may be rotated to change an approach angle of associated airfoils. A cylinder drives a piston rod to in turn cause a linkage system to vary the approach angle of the airfoils. The cylinder has a tailstock at an end remote from the piston rod. A spherical bearing mounts the tailstock. A bearing retainer provides a stop to prevent undue rotation of the tailstock relative to the bearing. A compressor and a gas turbine engine are also disclosed.

BACKGROUND OF THE INVENTION

This application relates to a bearing retainer that prevents undesired rotation of the actuator for a variable vane system.

Gas turbine engines are known, and typically include a fan delivering air into a compressor section. The air is compressed in the compressor section, and delivered downstream into a combustion section where it is mixed with fuel and ignited. Products of this combustion pass downstream over turbine rotors, driving them to rotate.

The compressor section typically includes a plurality of compressor stages having rotors carrying a plurality of rotating blades. Intermediate the compressor stages are static vanes, which serve to redirect the airflow between the compressor stages.

A desired approach angle for the air may vary during operation of the gas turbine engine, and dependent upon operational conditions. Thus, it is known to provide so-called variable vanes which are pivotably mounted such that their angle can be changed. Typically, a single actuator drives a ring to rotate, and this rotation causes the orientation of a plurality of vanes to be changed.

One known actuator includes a piston rod of a cylinder to cause the rotation of a bell crank. The cylinder is mounted at a rear end on a spherical bearing, and the piston is also mounted on a spherical bearing within a clevis.

The use of the spherical bearings allows some misalignment such as may be due to manufacturing tolerances or thermal displacement.

However, when stresses and force are placed on the actuator, and in particular the piston rod, the cylinder may rotate about its own axis. When this occurs, the cylinder or its mount structure may strike a mount structure associated with a housing. This is undesirable.

SUMMARY OF THE INVENTION

In a featured embodiment, a variable vane actuator has a plurality of vanes which may be rotated to change an approach angle of associated airfoils. A cylinder is mounted to drive a piston rod to in turn cause a linkage system to vary the approach angle of the airfoils. The cylinder has a tailstock at an end remote from the piston rod. The tailstock is pivotably mounted within a clevis, and on a bolt. A spherical bearing is between the bolt and tailstock, and includes an inner member riding on the bolt and having a spherical outer surface, and an outer member which moves with the tailstock, and a spherical inner surface moveable on the spherical outer surface of the inner member. The clevis includes two spaced ledges. A bearing retainer is between one of the ledges and the spherical bearing. The bearing retainer is formed of a material that is softer than a material forming the tailstock such that the bearing retainer provides a stop to prevent undue rotation of the tailstock and the outer member relative to the inner member.

In another embodiment according to the previous embodiment, the bearing retainer has a shape of a top hat, with an extension extending from a planer section. The planer section abuts the spherical bearing. The extension fits within an opening in one of the ledges. The bolt extends through the extension, through the planer portion, through the inner member, and then through a second of the ledges.

In another embodiment according to any of the previous embodiments, the bearing retainer is generally cylindrical.

In another embodiment according to any of the previous embodiments, the bearing retainer has a truncated portion associated with a limited circumferential extent of the bearing retainer. The truncated portion is positioned adjacent an under surface of the cylinder from which the tailstock extends.

In another embodiment according to any of the previous embodiments, the bearing retainer is formed of one of a composite or metal.

In another embodiment according to any of the previous embodiments, a first gap is defined between the bearing retainer and tailstock, and a second gap is defined between a second of the ledges and tailstock. The first gap is smaller than the second gap.

In another embodiment according to any of the previous embodiments, one of the ledges receives a head of the bolt.

In another featured embodiment, a compressor section has a plurality of compressor stages spaced for rotation about a central axis. A plurality of vanes is positioned between adjacent ones of the plurality of compressor stages, with the plurality of vanes provided with an airfoil for directing air to a downstream compressor stage. An approach angle of the plurality of airfoils is changeable by an actuator. The actuator includes a cylinder mounted to drive a piston rod to in turn cause a linkage system to vary the approach angle of the airfoils. The cylinder has a tailstock at an end remote from the piston rod, with the tailstock being pivotably mounted within a clevis, and on a bolt. A spherical bearing is between the bolt and tailstock, with the spherical bearing including an inner member riding on the bolt and having a spherical outer surface. An outer bearing member moves with the tailstock, and has a spherical inner surface moveable on the spherical outer surface of the inner member. The clevis includes two spaced ledges. A bearing retainer is between one of the ledges and the spherical bearing and tailstock. The bearing retainer is formed of a material that is softer than a material forming the tailstock such that the bearing retainer provides a stop to prevent undue rotation of the tailstock and the outer member relative to the inner member.

In another embodiment according to the previous embodiment, the bearing retainer has a shape of a top hat, with an extension extending from a planer section. The planer section abuts the spherical bearing. The extension fits within an opening in one of the ledges, with the bolt extending through the extension, through the planer portion, through the inner member, and then through a second of the ledges.

In another embodiment according to any of the previous embodiments, the bearing retainer is generally cylindrical.

In another embodiment according to any of the previous embodiments, the bearing retainer has a truncated portion associated with a limited circumferential extent of the bearing retainer, with the truncated portion positioned adjacent an under surface of the cylinder from which the tailstock extends.

In another embodiment according to any of the previous embodiments, the bearing retainer is formed of one of a composite or metal.

In another embodiment according to any of the previous embodiments, a first gap is defined between the bearing retainer and tailstock, and a second gap is defined between a second of the ledges and tailstock. The first gap is smaller than the second gap.

In another embodiment according to any of the previous embodiments, one of the ledges receives a head of the bolt.

In another featured embodiment, a gas turbine engine has a compressor section, a combustor, and a turbine section. The compressor section includes a plurality of compressor stages spaced for rotation about a central axis. A plurality of vanes is positioned between adjacent ones of the plurality of compressor stages, with the plurality of vanes being provided with an airfoil for directing air to a downstream compressor stage. An approach angle of the plurality of airfoils is changeable by an actuator. The actuator includes a cylinder mounted to drive a piston rod to in turn cause an actuator to vary the approach angle of the airfoils. The cylinder has a tailstock at an end remote from the piston rod. The tailstock is pivotably mounted within a clevis, and on a bolt. A spherical bearing is between the bolt and tailstock, and includes an inner member riding on the bolt and having a spherical outer surface, and an outer bearing member which moves with the tailstock. A spherical inner surface is moveable on the spherical outer surface of the inner member. The clevis includes two spaced ledges. A bearing retainer is between one of the ledges and the spherical bearing and tailstock. The bearing retainer is formed of a material that is softer than a material forming the tailstock such that the bearing retainer provides a stop to prevent undue rotation of the tailstock and the outer member relative to the inner member and the bolt.

In another embodiment according to any of the previous embodiments, the bearing retainer has a shape of a top hat, with an extension extending from a planer section. The planer section abuts the spherical bearing. The extension fits within an opening in one of the ledges, with the bolt extending through the extension through the planer portion, through the inner member, and then through a second of the ledges.

In another embodiment according to any of the previous embodiments, the bearing retainer is generally cylindrical.

In another embodiment according to any of the previous embodiments, the bearing retainer has a truncated portion associated with a limited circumferential extent of the bearing retainer. The truncated portion is positioned adjacent an under surface of the cylinder from which the tailstock extends.

In another embodiment according to any of the previous embodiments, a first gap is defined between the bearing retainer and tailstock, and a second gap is defined between a second of the ledges and the tailstock. The first gap is smaller than the second gap.

In another embodiment according to any of the previous embodiments, one of the ledges receives a head of the bolt.

These and other features of this application will be best understood from the following specification and drawings, the following of which is a brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A schematically shows a gas turbine engine.

FIG. 1B shows an alternative engine.

FIG. 2 shows an actuator structure for use in the FIG. 1 engine.

FIG. 3 is a cross-sectional view through a mount incorporated into the present invention.

FIG. 4 shows a detail of a top hat bearing retainer.

FIG. 5 is a perspective view of the bearing retainer.

FIG. 6 is a section along axis 6-6 of FIG. 3 showing rotation.

FIG. 7 shows rotation in a second embodiment.

DETAILED DESCRIPTION

FIG. 1A schematically illustrates a gas turbine engine 20. The gas turbine engine 20 is disclosed herein as a two-spool turbofan that generally incorporates a fan section 22, a compressor section 24, a combustor section 26 and a turbine section 28. Alternative engines might include an augmentor section (not shown) among other systems or features. The fan section 22 drives air along a bypass flowpath B while the compressor section 24 drives air along a core flowpath C for compression and communication into the combustor section 26 then expansion through the turbine section 28. Although depicted as a turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines including three-spool architectures. Also, industrial gas turbines will come within the scope of this application.

The engine 20 generally includes a low speed spool 30 and a high speed spool 32 mounted for rotation about an engine central longitudinal axis A relative to an engine static structure 36 via several bearing systems 38. It should be understood that various bearing systems 38 at various locations may alternatively or additionally be provided.

The low speed spool 30 generally includes an inner shaft 40 that interconnects a fan 42, a low pressure compressor 44 and a low pressure turbine 46. The inner shaft 40 is connected to the fan 42 through a geared architecture 48 to drive the fan 42 at a lower speed than the low speed spool 30. The high speed spool 32 includes an outer shaft 50 that interconnects a high pressure compressor 52 and high pressure turbine 54. A combustor 56 is arranged between the high pressure compressor 52 and the high pressure turbine 54. A mid-turbine frame 57 of the engine static structure 36 is arranged generally between the high pressure turbine 54 and the low pressure turbine 46. The mid-turbine frame 57 further supports bearing systems 38 in the turbine section 28. The inner shaft 40 and the outer shaft 50 are concentric and rotate via bearing systems 38 about the engine central longitudinal axis A which is collinear with their longitudinal axes.

The core airflow is compressed by the low pressure compressor 44 then the high pressure compressor 52, mixed and burned with fuel in the combustor 56, then expanded over the high pressure turbine 54 and low pressure turbine 46. The mid-turbine frame 57 includes airfoils 59 which are in the core airflow path. The turbines 46, 54 rotationally drive the respective low speed spool 30 and high speed spool 32 in response to the expansion.

As is clear, FIG. 1A is a highly schematic view. Among the components of the compressor section 24, are a plurality of compressor stages 300 in both the high pressure and low pressure compressors. The compressor stages 300 are each defined by a plurality of rotating blades. Intermediate the stages are a plurality of static vanes 301. The static vanes may be fixed, or may be variable vanes. The variable vanes have an airfoil that may be rotated to adjust an approach angle of the air from one compressor stage approaching the next downstream compressor stage.

FIG. 1B shows an alternative engine 420 that would also have a compressor with variable vanes. Engine 420 is shown to schematically include a compressor section 422 delivering compressed air into a combustor section 424. A turbine section 426 is downstream of the combustor section 424, and serves to drive the compressor 422. In addition, a generator 427 is shown schematically for generating electricity.

Additional turbine stages 428 may be driven by products of the combustion to in turn drive a generator 430. Engine 420 is an industrial gas turbine, such as may be utilized in land-based applications to generate electricity. The features of this application would apply to this type engine as well.

FIG. 2 shows an actuator drive 75 which includes a cylinder 80 that drives a piston rod 88 outwardly or inwardly. The cylinder driver may be fluid, or may be electrical, mechanical, etc. The piston is pivotally connected at 94 to a clevis 90. Clevis 90 drives a sync ring rod 92. As is known, the rod 92 causes a ring to rotate, and this then adjusts the angle of a plurality of vanes, such as the vanes 301 shown in FIG. 1. The actuation of the vanes, and the reason for changing the approach angle of the vanes are as known in the art.

This application relates to improvements in a tailstock mount, which mounts a tailstock 82 associated with the cylinder 80 in a clevis 84 on a static housing. As shown, a bolt 86 mounts the tailstock 82 in the clevis 84.

FIG. 3 is a cross-sectional view through this connection, and shows a nut 106 locking the bolt 86 in the clevis, and locking the tailstock 82 of the cylinder 80. As shown, the clevis 84 includes two side ledges 100, and the bolt 86 extends through openings in those two ledges 100. The tailstock 82 is mounted on the bolt 86 through a spherical bearing 102/104. The spherical bearing includes an inner spherical portion 104 which is fixed with the bolt 86, and an outer portion 102 which is fixed to the tailstock 82. As shown, a bearing retainer 110 forces the bearing against an opposed ledge 100. The bearing retainer 110 has the shape of a top hat, and includes an extending portion 111 received within an opening in one ledge 100, and a planer portion 112 which abuts the bearing. An edge 121 of the bearing retainer 110 faces the tailstock. The bolt 86 clamps the bearing retainer 110 and bearing inner spherical portion 104 against one side ledge.

As shown in FIG. 4, the retainer 110 has a flat edge 113 which is truncated compared to an otherwise cylindrical shape 115. The truncated portion 113 provides clearance adjacent to a lower surface 302 of the cylinder 80.

FIG. 5 shows details of the retainer 110.

As shown in FIG. 6, the tailstock 82, and the outer bearing portion 102 have rotated on the inner spherical bearing portion 104. In the past, this could allow the tailstock 82 to contact one of the ledges 100, which could cause damage to the ledge or the tailstock. However, as shown at 130, with this rotation, the tailstock is abutting a portion of the retainer 110 as shown at 130. This prevents further rotation.

The FIG. 7 discloses a distinct assembly 500 wherein the bearing retainer 210 is positioned adjacent the opposed ledge from the ledge that receives a head 300 of bolt 86. Again, with rotation, there is contact between retainer 210 and the tailstock as shown at 131. It should be understood the bearing retainer could be at either side.

Returning to FIG. 3, a first gap 113 between the edge 121 of the bearing retainer 110 and the tailstock 82 is less than a second gap 109 between the tailstock 82 and the opposed ledge 100. This results in the gap 315 also being greater than the gap 113. Thus, when misalignment, as illustrated in FIG. 6, occurs, the contact will occur between edge 121 and tailstock 82, rather than at the opposed side 215. The same gaps are found in the FIG. 7 assembly.

The retainer 110 is formed of a composite or metal such as aluminium or steel. Generally, the retainer 110 should be formed of a softer material than the material used for the actuator tailstock, or the bearing outer surface 102. Thus should there be damage due to the rotation, it will be the less expensive retainer 110 which is damaged.

While an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention. 

1. A variable vane actuator comprising: a plurality of vanes which may be rotated to change an approach angle of associated airfoils; a cylinder mounted to drive a piston rod to in turn cause a linkage system to vary the approach angle of said airfoils, said cylinder having a tailstock at an end remote from the piston rod, with said tailstock being pivotably mounted within a clevis, and on a bolt; a spherical bearing between said bolt and said tailstock, with said spherical bearing including an inner member riding on said bolt and having a spherical outer surface, and an outer member which moves with said tailstock, and has an spherical inner surface moveable on said spherical outer surface of said inner member; said clevis including two spaced ledges; and a bearing retainer between one of said ledges and said spherical bearing, said bearing retainer being formed of a material that is softer than a material forming said tailstock such that said bearing retainer provides a stop to prevent undue rotation of said tailstock and said outer member relative to said inner member.
 2. The variable vane actuator as set forth in claim 1, wherein said bearing retainer has a shape of a top hat, with an extension extending from a planer section, said planer section abutting said spherical bearing, and said extension fitting within an opening in said one of said ledges, with said bolt extending through said extension, through said planer portion, through said inner member, and then through a second of said ledges.
 3. The variable vane actuator as set forth in claim 1, wherein said bearing retainer is generally cylindrical.
 4. The variable vane actuator as set forth in claim 3, wherein said bearing retainer has a truncated portion associated with a limited circumferential extent of said bearing retainer, with said truncated portion being positioned adjacent an under surface of said cylinder from which said tailstock extends.
 5. The variable vane actuator as set forth in claim 1, wherein said bearing retainer is formed of one of a composite or metal.
 6. The variable vane actuator as set forth in claim 1, wherein a first gap is defined between said bearing retainer and said tailstock, and a second gap is defined between a second of said ledges and said tailstock, and said first gap being smaller than said second gap.
 7. The variable vane actuator as set forth in claim 1, wherein said one of said ledges receives a head of said bolt.
 8. A compressor section comprising: a plurality of compressor stages spaced for rotation about a central axis; a plurality of vanes positioned between adjacent ones of said plurality of compressor stages, with said plurality of vanes being provided with an airfoil for directing air to a downstream compressor stage, and an approach angle of said plurality of airfoils being changeable by an actuator; the actuator including a cylinder mounted to drive a piston rod to in turn cause a linkage system to vary the approach angle of said airfoils, said cylinder having a tailstock at an end remote from the piston rod, with said tailstock being pivotably mounted within a clevis, and on a bolt; a spherical bearing between said bolt and said tailstock, with said spherical bearing including an inner member riding on said bolt and having a spherical outer surface, and an outer bearing member which moves with said tailstock, and has a spherical inner surface moveable on said spherical outer surface of said inner member; said clevis including two spaced ledges; and a bearing retainer between one of said ledges and said spherical bearing and said tailstock, said bearing retainer being formed of a material that is softer than a material forming said tailstock such that said bearing retainer provides a stop to prevent undue rotation of said tailstock and said outer member relative to said inner member.
 9. The compressor as set forth in claim 8, wherein said bearing retainer has a shape of a top hat, with an extension extending from a planer section, said planer section abutting said spherical bearing, and said extension fitting within an opening in said one of said ledges, with said bolt extending through said extension, through said planer portion, through said inner member, and then through a second of said ledges.
 10. The compressor as set forth in claim 8, wherein said bearing retainer is generally cylindrical.
 11. The compressor as set forth in claim 10, wherein said bearing retainer has a truncated portion associated with a limited circumferential extent of said bearing retainer, with said truncated portion being positioned adjacent an under surface of said cylinder from which said tailstock extends.
 12. The compressor as set forth in claim 8, wherein said bearing retainer is formed of one of a composite or metal.
 13. The compressor as set forth in claim 8, wherein a first gap is defined between said bearing retainer and said tailstock, and a second gap is defined between a second of said ledges and said tailstock, and said first gap being smaller than said second gap.
 14. The compressor as set forth in claim 8, wherein said one of said ledges receives a head of said bolt.
 15. A gas turbine engine comprising: a compressor section, a combustor, and a turbine section; said compressor section including a plurality of compressor stages spaced for rotation about a central axis; a plurality of vanes positioned between adjacent ones of said plurality of compressor stages, with said plurality of vanes being provided with an airfoil for directing air to a downstream compressor stage, and an approach angle of said plurality of airfoils being changeable by an actuator; the actuator including a cylinder mounted to drive a piston rod to in turn cause an actuator to vary the approach angle of said airfoils, said cylinder having a tailstock at an end remote from the piston rod, with said tailstock being pivotably mounted within a clevis, and on a bolt; a spherical bearing between said bolt and said tailstock, with said spherical bearing including an inner member riding on said bolt and having a spherical outer surface, and an outer bearing member which moves with said tailstock, and has a spherical inner surface moveable on said spherical outer surface of said inner member; said clevis including two spaced ledges; and a bearing retainer between one of said ledges and said spherical bearing and said tailstock, said bearing retainer being formed of a material that is softer than a material forming said tailstock such that said bearing retainer provides a stop to prevent undue rotation of said tailstock and said outer member relative to said inner member and said bolt.
 16. The engine as set forth in claim 15, wherein said bearing retainer has a shape of a top hat, with an extension extending from a planer section, said planer section abutting said spherical bearing, and said extension fitting within an opening in said one of said ledges, with said bolt extending through said extension through said planer portion, through said inner member, and then through a second of said ledges.
 17. The engine actuator as set forth in claim 15, wherein said bearing retainer is generally cylindrical.
 18. The engine as set forth in claim 17, wherein said bearing retainer has a truncated portion associated with a limited circumferential extent of said bearing retainer, with said truncated portion being positioned adjacent an under surface of said cylinder from which said tailstock extends.
 19. The engine as set forth in claim 15, wherein a first gap is defined between said bearing retainer and said tailstock, and a second gap is defined between a second of said ledges and said tailstock, and said first gap being smaller than said second gap.
 20. The engine as set forth in claim 15, wherein said one of said ledges receives a head of said bolt. 